** GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing **

GOES-!6 Visible (0.64 µm) images (above) revealed the presence of a well-defined lake breeze boundary on 14 June 2017, which extended well inland from Lake Superior across northeastern Minnesota and northwestern Wisconsin. This shallow pool of lake-cooled air was acting to suppress the formation of inland cumulus clouds and maintain marine layer fog/stratus over the water and the adjacent coast — both of which slowed the warming of surface air temperatures. For example, in northwestern Wisconsin, Hayward Sawyer County Airport (KHYR) reached an afternoon high temperature of 81º F, while not far to the northwest Duluth Sky Harbor Airport (KDYT) only reached an afternoon high of 52º F as fog and stratus shrouded the site and held temperatures in the 40s F much of the day. Note that a few bore-like wave structures were seen in the lake stratus.

A comparison of Suomi NPP VIIRS Visible (0.64 µm) imagery at 1803 UTC with RTMA surface winds at 18 UTC (below) showed the flow and cloud features associated with the lake breeze.

A large Mesoscale Convective System (MCS) developed and intensified over western South Dakota during the nighttime hours of 10 June – 11 June 2017, evolving into a bow echo that spread a swath of hail and strong winds from central/eastern South Dakota across Minnesota and into Wisconsin and Michigan (SPC storm reports: 10 June | 11 June). Image toggles between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) at 0734 UTC or 2:34 am Central Time (above) and 0916 UTC or 4:16 am Central Time (below) showed numerous well-defined overshooting tops and cloud-top gravity waves over South Dakota. The coldest cloud-top infrared brightness temperature on the 0916 UTC image was -88º C (darkviolet color enhancement). Since the Moon was in the Waning Gibbous phase (at 97% of Full), its ample illumination provided vivid examples of the “visible image at night” capability of the Day/Night Band; several bright white “lightning streaks” were also evident, a signature of cloud top illumination by intense lightning activity.

During the subsequent daytime hours of 11 June, GOES-16 Visible (0.64 µm) and Infrared Window (10.3 µm) images (below) showed the eastward progression of the MCS across Minnesota into western Wisconsin.

A well-defined train of wind shear vortices was revealed on GOES-16 Water Vapor images — Upper-level (6.2 µm), Mid-level (6.9 µm) and Lower-level (7.3 µm) — propagating westward over the Great Lakes on 07 June 2017(above).

A larger-scale view using Mid-level 6.9 µm images (below) showed additional (and larger) vortices which were moving eastward over the Ohio River Valley. Pilot reports of turbulence are plotted on the water vapor images, and many of those reports appeared to be in the general vicinity of the vortices.

GOES-16 Water Vapor (6.9 µm) images [click to play animation]

A 3-hour-interval Mid-Level Wind Shear product derived from GOES-13 (GOES-East) atmospheric motion vectors (AMVs) is shown below. An elongated cyclonic shear axis was present from the Northeast US to the Ohio River Valley, and the location of the water vapor vortices appeared to correspond to the wind shear gradients along the northern and southern edges of this axis.